A catheter is a thin and long tube-shaped medical treatment tool. The catheter is inserted into human body and is used to diagnose and cure a disease such as drug injection to a lesion or removal of tumor.
In vascular intervention, after the catheter enters the blood vessel where a lesion exists, the lesion is treated by injecting drugs. If the drug is delivered to a tissue outside the lesion, the tissue outside the lesion necrotizes. Therefore, it is important to position the front end of the catheter as close to the lesion as possible. Accordingly, in a blood vessel with many branches, the catheter capable of steering the front end of the catheter in a desired direction is being developed and used. FIG. 1 is a cross sectional view of a conventional direction-controllable drug injection catheter. Referring to FIG. 1, the catheter 10 includes a flexible tube 11, a drug injection channel 12c formed within the flexible tube 11, two wire channels 12a and 12b formed to have the drug injection channel 12c placed therebetween, and two steering wires 13a and 13b which are positioned in the two wire channels 12a and 12b respectively. The catheter 10 is steered by the two steering wires 13a and 13b. However, in addition to the conventional direction-controllable drug injection channel, two steering channels through which the two steering wires pass respectively are included, so that there is a limit to reduce the thickness of the catheter. Also, the conventional direction-controllable drug injection catheter has a complex structure because it includes a separate configuration for steering.